A conventional refrigeration system has been known which comprises a refrigerant circuit including a compressor, a condenser, a pressure reducing mechanism, and an evaporator and the refrigerant circuit forms a refrigeration cycle using an HCFC refrigerant such as R22. Of these element devices of the refrigerant circuit, the compressor plays an important role of increasing the pressure of the refrigerant. Therefore, refrigeration oil is required for smooth operation of the compressor.
On the other hand, refrigeration systems employing an HFC refrigerant use a synthetic oil as a refrigeration oil.
Problems that the Invention Intends to Solve
However, such a synthetic oil is degraded when contaminated with air and moisture, thereby causing a problem of increasing the total acid number of the synthetic oil. On the other hand, resin materials have been utilized as an insulating material for an electric motor of the compressor. However, the resin materials undergo deterioration in strength (for example, deterioration in tensile strength) during the rise in total acid number. This may cause burning out of the electric motor in the worst case.
Further, for the case of using a resin material such as polyethylene terephthalate (PET), it is the resin material itself that causes hydrolysis during the rise in temperature due to refrigeration operations, when coexisting with moisture. As a result, the deterioration of the resin material will be aggravated.
Contamination with air and moisture occurs at the time of manufacture of the element devices of the refrigerant circuit and at the time of installation of the system in the field. Therefore, the amount of such contamination can be reduced by making a change in the manufacture method and process and by reinforcing the product quality control at the time of manufacture of the system. On the other hand, at the time of installation of the system, it is necessary to take some measures for achieving improvements in the degree of ultimate vacuum when drawing vacuum, for extending the length of time taken to draw vacuum, and for providing improvements in vacuum pump performance.
Therefore, with respect to refrigeration systems provided with a compressor, there is the demand for further improvements in system reliability as well as in system handling ease.
Bearing in mind the aforementioned problems, the present invention was made. Accordingly, an object of the present invention is to provide improvements in system reliability as well as in system handling ease.